I. Field
The following description relates generally to digital rights management and more particularly to an efficient key hierarchy for delivery of multimedia content.
II. Background
As Third Generation (3G) mobile systems and other cellular networks are deployed, new Internet Protocol (IP) packet data based services are emerging. A service area that network operators are seeking to exploit involves the distribution of video content to the mass market. High-quality video is a type of data-intensive content. Consumer experience with home viewing options provides network operators and content providers with target markets that have predefined user expectations. These user expectations combined with mobility, attractive business models, network control and management, access control, and device capabilities present complex challenges to network operators and content providers.
Protection of distributed content is a challenge that has arisen to guard against unauthorized copying and to control, either directly or indirectly, the content distribution. Content providers typically require that a content distribution system have the ability to provide Digital Rights Management (DRM), which refers to any of several technical arrangements that provide control for the user of distributed material on electronic devices with such measures installed. An underlying component for content distribution systems is the feature of encryption/decryption of media during transmission/receipt, such as in a subscription-based content distributions service. DRM software can provide the underlying encryption/decryption algorithms, hashing and authentication algorithm implementations used on both the client and the server portions. DRM can also provide license download and secure file-storage features for the client.
Two types of cryptosystems or cryptography techniques that may be utilized in DRM systems are symmetric cryptography and asymmetric cryptography. In symmetric key cryptography, the same key is used for both encryption and decryption. Examples of symmetric key cryptography include Data Encryption Standard (DES) and Advanced Encryption Standard (AES) systems. In asymmetric cryptography, also known as public-key cryptography, each user has a public key and a private key. Encryption is performed with the public key while decryption is performed with the private key. Examples of asymmetric cryptography include the Rivest, Shamir and Adleman (RSA) algorithm and Elliptic Curve Cryptography (ECC). Symmetric key cryptography is fast compared to asymmetric key cryptography, but it suffers from the drawback of having to communicate the shared keys secretly to the communicating entities. Asymmetric cryptography, as its name implies, unevenly divides processing demands based on the use of the public and private keys.